President Trump at the White House on May 8 in Washington. (Al Drago/Bloomberg)

THE NEW YORK TIMES on Tuesday revealed 10 years of President Trump’s tax information, depicting a tumultuous period in which Mr. Trump appears to have squandered a fortune on vanity projects such as the Trump Taj Mahal Hotel and Casino and Trump Shuttle. In other words, the president has been exposed as a disastrously poor businessman, at least through 1994. Which has us wondering: At this point, what does Mr. Trump have left to hide?

The Times reported that Mr. Trump’s roughly $1 billion in losses made him one of the biggest financial failures of this era. To be clear, though reported on his personal tax forms, not all of this cumulative loss represented personal wealth; Mr. Trump’s creditors also took a bath. The president on Wednesday responded by arguing that quirks in the real estate business explain the barrels of red ink he reported to the Internal Revenue Service. But the Times found that Mr. Trump’s performance was particularly poor even relative to other business owners in a position similar to his.

The Times’s analysis of the records contains more indications of sleaziness than business acumen. Mr. Trump made some profits by buying stock in companies and making it seem as though he planned to launch a takeover. He had no intention of doing so, but he gained when he sold his holdings after the resulting blip in the companies’ stock price. Investors eventually caught on, and Mr. Trump’s losses continued to mount.

Meanwhile, Mr. Trump was building an image as a business genius with his bestseller, “The Art of the Deal.” He would deceive the public once again in the 2016 presidential race, when he ran on his supposed business success (and repeatedly promised to release his tax returns). Perhaps Mr. Trump was referring to the period following the calamitous decade shown in the newly revealed tax documents. If so, he has an opportunity to prove that his is a great comeback story — and that the basis of his presidential campaign was not a lie — by finally releasing the rest of his tax returns. At this point, his most embarrassing tax information would seem to be out, unless there is something else he wants kept from the public.

Voters should not have to engage in these sorts of speculations. Ever since President Richard M. Nixon proclaimed that “people have got to know whether or not their president is a crook,” presidents and major-party candidates have released their tax information. In the case of Mr. Trump, the latest revelations show that this norm was even more important for him to follow, because his image as an effective leader was built on his purported business achievement, not a record of accomplishment in public life.

Yet Mr. Trump’s insistence on secrecy has led his treasury secretary, Steven Mnuchin, to defy the law’s clear instructions by refusing to turn over the president’s recent tax returns to House Democrats, a move that judges will almost certainly rebuke in time. New York state lawmakers advanced a bill on Wednesday that would allow the disclosure of Mr. Trump’s state tax returns to select members of Congress, and it seems likely to pass.

But it should not fall to courts or state officials to enforce a norm that previously did not need to be mandated. The president should end this drama now and finally release the rest of his tax returns.